1. Field of the Invention
This invention relates to a method of manufacturing a rigid-flex printed wiring board comprising a flexible substrate and rigid substrates integral therewith.
2. Description of the Related Art
U.S. Pat. No. 4,037,047 discloses a typical conventional method of manufacturing a rigid-flex printed wiring board which comprises a flexible substrate made of polyamide and previously formed with a circuit pattern and rigid substrates made of epoxy-resin impregnated glass fiber and attached to both surfaces of the flexible substrate by means of adhesive layers to form a substrate composition. A window-type opening is formed in the portion of each adhesive layer on which the respective rigid substrate is attached. Through holes are formed at the required portions of the rigid substrates and the inner wall of each through hole is plated for electrical conduction. Thereafter outer circuitry is formed on the rigid substrates. Finally, the unwanted portion is removed from the rigid substrates by means of a punch or the like and a rigid-flex printed wiring board is completed.
In the conventional manufacturing method, slots are previously formed between the required portions and the unwanted portion of each rigid substrate in order to remove the unwanted portion from the rigid substrate. In this structure, a plating solution and/or an etching solution tends to enter the spaces between the flexible substrate and the rigid substrates through the slots from the outside of the substrate composition. Further, copper separated from the plating solution tends to be deposited on the surfaces of the flexible substrate in the spaces; plating solution and/or etching solution in such spaces comes out in the succeeding processes to reduce a water-cleaning effect; and/or such solutions enter the exposing equipment and corrode the same when evacuation is carried out in the exposing process.